Tissue resecting systems and methods

ABSTRACT

A tissue resecting system includes an assembly having first and second tubular members. An electrical motor drive and controller moves the second member to resect tissue received in a window of the first member. A tachometer sends motor drive rotational signals to the controller, and the controller modulates a motor voltage in response to the signals from the tachometer both to drive the second member at a predetermined speed and to calculate resistance to driving the second member at the predetermined speed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/277,897, filed Feb. 15, 2019, which is a continuation of U.S.application Ser. No. 15/291,655, filed Oct. 12, 2016, now U.S. Pat. No.10,238,412, which is a continuation of U.S. application Ser. No.14/249,161, filed Apr. 9, 2014, now U.S. Pat. No. 9,486,233 whichapplication claims the benefit of U.S. Provisional Application No.61/816,371, filed Apr. 26, 2013, the full disclosures of which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates systems and methods for the resection andextraction of tissue from the interior of a patient's body, for exampleuterine fibroid tissue, prostate tissue or joint tissue.

BACKGROUND OF THE INVENTION

Uterine fibroids are non-cancerous tumors that develop in the wall ofuterus. Such fibroids occur in a large percentage of the femalepopulation, with some studies indicating that up to 40 percent of allwomen have fibroids. Uterine fibroids can grow over time to be severalcentimeters in diameter and symptoms can include menorrhagia,reproductive dysfunction, pelvic pressure and pain.

One current treatment of fibroids is hysteroscopic resection ormyomectomy which involves transcervical access to the uterus with ahysteroscope together with insertion of a cutting instrument through aworking channel in the hysteroscope. The cutting instrument may be amechanical tissue cutter or an electro surgical resection device such asa cutting loop. Mechanical cutting devices are disclosed in U.S. Pat.Nos. 7,226,459; 6,032,673 and 5,730,752 and U.S. Published Patent Appl.2009/0270898. An electrosurgical resecting device is disclosed in U.S.Pat. No. 5,906,615.

While hysteroscopic resection can be effective in removing uterinefibroids, many commercially available instrument are too large indiameter and thus require anesthesia in an operating room environment.Conventional resectoscopes require cervical dilation to about 9 mm. Whatis needed is a system that can effectively resect and remove fibroidtissue through a small diameter hysteroscope.

SUMMARY OF THE INVENTION

The present invention provides methods for resecting and removing targettissue from a patient's body, such as fibroids from a uterus. The tissueis cut, captured in a probe, catheter, or other tissue-removal device,and expelled from the capture device by vaporizing a fluid, typically aliquid, adjacent to the captured tissue in order to propel the tissuefrom the device, typically through an extraction or other lumen presentin a body or shaft of the device. Exemplary embodiments of the tissueremoval device comprise a reciprocating blade, tubular cutter, or thelike, where the blade may be advanced past a resecting window on thedevice in order to sever a tissue strip and capture the strip within aninterior volume or receptacle on the device. The liquid or otherexpandable fluid is also present in the device, and energy is applied tothe fluid in order to cause rapid expansion, e.g., vaporization, inorder to propel the severed tissue strip through the extraction lumen.In this way, the dimensions of the extraction lumen can be reduced,particularly in the distal regions of the device where size is ofcritical.

In a first method, according to the present invention, tissue isextracted from an interior of the patient's body by capturing a tissuevolume in a distal portion of an interior passageway of an elongatedprobe. A fluid located distal to the captured tissue volume is expanded,which proximally propels the tissue volume from the device. The fluidtypically comprises a liquid, and the expansion typically comprises aliquid-to-vapor phase transition. In other cases, the fluid might be agas where the expansion results from very rapid heating. In preferredembodiments, the phase transition is achieved by applying electricalenergy in an amount sufficient to vaporize the liquid, typicallyapplying RF current between first and second polarity electrodes, whereat least one of the electrodes is disposed on a distal side of thecaptured tissue volume.

The liquid or other fluid may be provided to a working end of the probein various ways. Often, the liquid or other fluid is provided from afluid-filled space in the patient's body, for example from a distensionfluid filled in the cavity to be treated, such as the uterus.Alternatively, the liquid or other fluid may be provided from a remotesource through a passageway in the probe. The liquid volume to bevaporized is typically in the range from 0.004 mL to 0.080 mL.

The tissue may be captured in a variety of ways. For example, the tissuemay be resected with a blade number or alternatively with an RFelectrode. In either case, the resected tissue may then be captured orsequestered within an interior passageway within the blade itself and/orwithin another portion of the probe. In addition to the propulsion forcecaused by the vaporizing fluid, the present invention might also rely onapplying a negative pressure to a proximal end of the anteriorpassageway to assist in drawing the tissue in a proximal direction fromthe extraction lumen.

In a further method according to the present invention, tissue isremoved from the interior of a patient's body by engaging a tubularresection member against the targeted tissue. An RF electrodearrangement on the device is energized to electrosurgically resect thetissue, and the same or a different RF electrode is used to vaporize aliquid to apply a positive fluid pressure to a distal surface of theresected tissue. Usually, the same RF electrode arrangement is used toboth electrosurgically resect the tissue and to vaporize the liquid. Insuch instances, the resecting member carrying the RF electrode isusually first advanced to electrosurgically resect the tissue andthereafter advanced into the liquid to vaporize the liquid. The liquidis usually present in a chamber or other space having an activeelectrode at a distal end thereof, and the RF electrode arrangement onthe exterior of the device comprises a return electrode. In this way,with the smaller active electrode on the distal side of the tissue, theenergy which vaporizes the liquid will be concentrated in the chamber onthe distal side of the tissue, thus causing rapid vaporization of theliquid and propulsion of the tissue through the extraction lumen.

In a third method according to the present invention, tissue is resectedand extracted from the interior of a patient's body by reciprocating aresecting member within a tubular assembly to sever a tissue strip. Thesevered tissue strip is captured in an extraction lumen of the tubularassembly, and a phase transition is caused in a fluid distal to thetissue strip to thereby apply a proximally directed expelling orpropulsion force to the tissue strip. The phase transition may be causedby applying energy from any one of a variety of energy sources,including an ultrasound transducer, a high-intensity focused ultrasound(HIFU) energy source, a laser energy source, a light or optical energysource, a microwave energy source, a resistive heat source, or the like.Typically, the resection device will carry the energy source, and theenergy source is also used to effect resection of the tissue. In thisway the resection device can also carry the energy source into the fluidafter the tissue has been cut, and the resecting and vaporization stepscan be performed sequentially as the resection device first movesthrough the tissue and then into the liquid or other fluid to bevaporized.

In a still further method according to the present invention, tissue isresected and extracted by first resecting the tissue with areciprocating resecting member over an extending stroke and a retractingstroke within a sleeve. The extending stroke cuts and captures tissuewhich has been drawn through a tissue-receiving window in the sleeve.Vaporization of a liquid distal to the captured tissue is caused by theresecting member while the resecting member is in a transition rangebetween extension and retraction. The tissue is typically captured inthe tissue extraction lumen formed at least partially in the resectingmember. The resecting member typically carries a first resectionelectrode, and a second electrode is typically disposed at a distal endof the sleeve. Thus, RF current may be delivered to the resectionelectrode and the second electrode in order to both effect resection ofthe tissue over the extending stroke of the resection device and to alsoeffect vaporization of the fluid while the resection device is in thetransition range.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view of an assembly including a hysteroscope and atissue resecting device corresponding to the invention that is insertedthrough a working channel of the hysteroscope.

FIG. 2 is a schematic perspective view of a fluid management system usedfor distending the uterus and for assisting in electrosurgical tissueresection and extraction.

FIG. 3 is a cross-sectional view of the shaft of the hysteroscope ofFIG. 1 showing various channels therein.

FIG. 4 is a schematic side view of the working end of theelectrosurgical tissue resecting device of FIG. 1 showing an outersleeve and a reciprocating inner sleeve and an electrode arrangement.

FIG. 5 is a schematic perspective view of the working end of the innersleeve of FIG. 4 showing its electrode edge.

FIG. 6A is a schematic cut-away view of a portion of outer sleeve, innerRF resecting sleeve and a tissue-receiving window of the outer sleeve.

FIG. 6B is a schematic view of a distal end portion another embodimentof inner RF resecting sleeve.

FIG. 7A is a cross sectional view of the inner RF resecting sleeve ofFIG. 6B taken along line 7A-7A of FIG. 6B.

FIG. 7B is another cross sectional view of the inner RF resecting sleeveof FIG. 6B taken along line 7B-7B of FIG. 6B.

FIG. 8 is a schematic view of a distal end portion of another embodimentof inner RF resecting sleeve.

FIG. 9A is a cross sectional view of the RF resecting sleeve of FIG. 8taken along line 9A-9A of FIG. 8.

FIG. 9B is a cross sectional view of the RF resecting sleeve of FIG. 8taken along line 9B-9B of FIG. 8.

FIG. 10A is a perspective view of the working end of the tissueresecting device of FIG. 1 with the reciprocating RF resecting sleeve ina non-extended position.

FIG. 10B is a perspective view of the tissue resecting device of FIG. 1with the reciprocating RF resecting sleeve in a partially extendedposition.

FIG. 10C is a perspective view of the tissue resecting device of FIG. 1with the reciprocating RF resecting sleeve in a fully extended positionacross the tissue-receiving window.

FIG. 11A is a sectional view of the working end of the tissue resectingdevice of FIG. 10A with the reciprocating RF resecting sleeve in anon-extended position.

FIG. 11B is a sectional view of the working end of FIG. 10B with thereciprocating RF resecting sleeve in a partially extended position.

FIG. 11C is a sectional view of the working end of FIG. 10C with thereciprocating RF resecting sleeve in a fully extended position.

FIG. 12A is an enlarged sectional view of the working end of tissueresecting device of FIG. 11B with the reciprocating RF resecting sleevein a partially extended position showing the RF field in a first RF modeand plasma resection of tissue.

FIG. 12B is an enlarged sectional view of the working end of FIG. 11Cwith the reciprocating RF resecting sleeve almost fully extended andshowing the RF fields switching to a second RF mode from a first RF modeshown in FIG. 12A.

FIG. 12C is an enlarged sectional view of the working end of FIG. 11Cwith the reciprocating RF resecting sleeve again almost fully extendedand showing the explosive vaporization of a captured liquid volume toexpel resected tissue in the proximal direction.

FIG. 13 is an enlarged perspective view of a portion of the working endof FIG. 12C showing an interior chamber and a fluted projecting element.

FIG. 14 is a sectional view of the working end of FIG. 12C showing aninterior chamber and a variation of a projecting element.

FIG. 15 is a sectional view of the working end of FIG. 12C showing aninterior chamber and a variation of a projecting element configured toexplosively vaporize the captured liquid volume.

FIG. 16A is a perspective view of an alternative working end with arotational resection device in a window open position.

FIG. 16B is a perspective view of the working end of FIG. 16A with therotating resecting element in a second position.

FIG. 16C is a view of the working end of FIGS. 16A-16B with the rotatingresecting element in a third position.

FIG. 17 is an exploded view of the outer sleeve of the working end ofFIGS. 16A-16C showing the mating components comprising a ceramic bodyand a metal tube.

FIG. 18 is a view of the inner sleeve of the working end of FIGS.16A-16C de-mated from the outer sleeve.

FIG. 19 is an exploded view of the inner sleeve of FIG. 18 showing themating components comprising a ceramic body and a metal tube.

FIG. 20A is a cross sectional view of the working end of FIGS. 16A-16Cwith the rotating inner sleeve in a first position resecting tissue in afirst RF mode.

FIG. 20B is a cross sectional view of the working end of FIG. 20A withthe rotating inner sleeve in a second window-closed position with asecond RF mode vaporizing saline captured in the interior extractionchannel.

FIG. 21 is a longitudinal sectional view corresponding to the view ofFIG. 20B with the rotating inner sleeve in a window-closed position andwith the second RF mode vaporizing saline captured in the interiorextraction channel to expel tissue proximally.

FIG. 22 is a view of an alternative embodiment of a metal tube componentof an inner sleeve.

FIG. 23 is a view of an alternative embodiment of a metal tube componentof an inner sleeve.

FIG. 24 is a perspective view of an alternative probe that is configuredto stop the inner rotating sleeve in a particular position.

FIG. 25A is a schematic illustration of a resecting device showing amotor drive system of the invention in a first position.

FIG. 25B is a schematic illustration similar to FIG. 25A showing themotor drive system in a second position.

FIG. 26 is a chart representing a method of the invention formaintaining a selected rotational speed of a drive system component.

FIG. 27 is a chart representing a method stopping movement of aresecting sleeve at a predetermined position relative to a tissuereceiving window.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates an assembly that comprises an endoscope 50 used forhysteroscopy together with a tissue-extraction device 100 extendingthrough a working channel 102 of the endoscope. The endoscope orhysteroscope 50 has a handle 104 coupled to an elongated shaft 105having a diameter of 5 mm to 7 mm. The working channel 102 therein maybe round, D-shaped or any other suitable shape. The endoscope shaft 105is further configured with an optics channel 106 and one or more fluidinflow/outflow channels 108 a, 108 b (FIG. 3) that communicate withvalve-connectors 110 a, 110 b configured for coupling to a fluid inflowsource 120 thereto, or optionally a negative pressure source 125 (FIGS.1-2). The fluid inflow source 120 is a component of a fluid managementsystem 126 as is known in the art (FIG. 2) which comprises a fluidcontainer 128 and pump mechanism 130 which pumps fluid through thehysteroscope 50 into the uterine cavity. As can be seen in FIG. 2, thefluid management system 126 further includes the negative pressuresource 125 (which can comprise an operating room wall suction source)coupled to the tissue resecting device 100. The handle 104 of theendoscope includes the angled extension portion 132 with optics to whicha videoscopic camera 135 can be operatively coupled. A light source 136also is coupled to light coupling 138 on the handle of the hysteroscope50. The working channel 102 of the hysteroscope is configured forinsertion and manipulation of the tissue resecting and extracting device100, for example to treat and remove fibroid tissue. In one embodiment,the hysteroscope shaft 105 has an axial length of 21 cm, and cancomprise a 0° scope, or 15° to 30° scope.

Still referring to FIG. 1, the tissue resecting device 100 has a highlyelongated shaft assembly 140 configured to extend through the workingchannel 102 in the hysteroscope. A handle 142 of the tissue resectingdevice 100 is adapted for manipulating the electrosurgical working end145 of the device. In use, the handle 142 can be manipulated bothrotationally and axially, for example, to orient the working end 145 toresect targeted fibroid tissue. The tissue resecting device 100 hassubsystems coupled to its handle 142 to enable electrosurgical resectionof targeted tissue. A radiofrequency generator or RF source 150 andcontroller 155 are coupled to at least one RF electrode carried by theworking end 145 as will be described in detail below. In one embodimentshown in FIG. 1, an electrical cable 156 and negative pressure source125 are operatively coupled to a connector 158 in handle 142. Theelectrical cable couples the RF source 150 to the electrosurgicalworking end 145. The negative pressure source 125 communicates with atissue-extraction channel 160 in the shaft assembly 140 of the tissueextraction device 100 (FIG. 4).

FIG. 1 further illustrates a seal housing 162 that carries a flexibleseal 164 carried by the hysteroscope handle 104 for sealing the shaft140 of the tissue resecting device 100 in the working channel 102 toprevent distending fluid from escaping from a uterine cavity.

In one embodiment as shown in FIG. 1, the handle 142 of tissue resectingdevice 100 includes a motor drive 165 for reciprocating or otherwisemoving a resecting component of the electrosurgical working end 145 aswill be described below. The handle 142 optionally includes one or moreactuator buttons 166 for actuating the device. In another embodiment, afootswitch can be used to operate the device. In one embodiment, thesystem includes a switch or control mechanism to provide a plurality ofreciprocation speeds, for example 1 Hz, 2 Hz, 3 Hz, 4 Hz and up to 8 Hz.Further, the system can include a mechanism for moving and locking thereciprocating resecting sleeve in a non-extended position and in anextended position. Further, the system can include a mechanism foractuating a single reciprocating stroke.

Referring to FIGS. 1 and 4, an electrosurgical tissue resecting devicehas an elongate shaft assembly 140 extending about longitudinal axis 168comprising an exterior or first outer sleeve 170 with passageway orlumen 172 therein that accommodates a second or inner sleeve 175 thatcan reciprocate (and optionally rotate or oscillate) in lumen 172 toresect tissue as is known in that art of such tubular resection devices. In one embodiment, the tissue-receiving window 176 in the outersleeve 170 has an axial length ranging between 10 mm and 30 mm andextends in a radial angle about outer sleeve 170 from about 45° to 210°relative to axis 168 of the sleeve. The outer and inner sleeves 170 and175 can comprise a thin-wall stainless steel material and function asopposing polarity electrodes as will be described in detail below. FIGS.6A-8 illustrate insulative layers carried by the outer and inner sleeves170 and 175 to limits, control and/or prevent unwanted electricalcurrent flows between certain portions of the sleeve. In one embodiment,a stainless steel outer sleeve 170 has an O.D. of 0.143″ with an I.D. of0.133″ and with an inner insulative layer (described below) the sleevehas a nominal I.D. of 0.125″. In this embodiment, the stainless steelinner sleeve 175 has an O.D. of 0.120″ with an I.D. of 0.112″. The innersleeve 175 with an outer insulative layer has a nominal O.D. of about0.123″ to 0.124″ to reciprocate in lumen 172. In other embodiments,outer and or inner sleeves can be fabricated of metal, plastic, ceramicof a combination thereof. The cross-section of the sleeves can be round,oval or any other suitable shape.

As can be seen in FIG. 4, the distal end 177 of inner sleeve 175comprises a first polarity electrode with distal resecting electrodeedge 180 about which plasma can be generated. The electrode edge 180also can be described as an active electrode during tissue resectionsince the electrode edge 180 then has a substantially smaller surfacearea than the opposing polarity or return electrode. In one embodimentin FIG. 4, the exposed surfaces of outer sleeve 170 comprises the secondpolarity electrode 185, which thus can be described as the returnelectrode since during use such an electrode surface has a substantiallylarger surface area compared to the functionally exposed surface area ofthe active electrode edge 180.

In one aspect of the invention, the inner sleeve or resecting sleeve 175has an interior tissue extraction lumen 160 with first and secondinterior diameters that are adapted to electrosurgically resect tissuevolumes rapidly—and thereafter consistently extract the resected tissuestrips through the highly elongated lumen 160 without clogging. Nowreferring to FIGS. 5 and 6A, it can be seen that the inner sleeve 175has a first diameter portion 190A that extends from the handle 142(FIG. 1) to a distal region 192 of the sleeve 175 wherein the tissueextraction lumen transitions to a smaller second diameter lumen 190Bwith a reduced diameter indicated at B which is defined by the electrodesleeve element 195 that provides resecting electrode edge 180. The axiallength C of the reduced cross-section lumen 190B can range from about 2mm to 20 mm. In one embodiment, the first diameter A is 0.112″ and thesecond reduced diameter B is 0.100″. As shown in FIG. 5, the innersleeve 175 can be an electrically conductive stainless steel and thereduced diameter electrode portion also can comprise a stainless steelelectrode sleeve element 195 that is welded in place by weld 196 (FIG.6A). In another alternative embodiment, the electrode and reduceddiameter electrode sleeve element 195 comprises a tungsten tube that canbe press fit into the distal end 198 of inner sleeve 175. FIGS. 5 and 6Afurther illustrates the interfacing insulation layers 202 and 204carried by the first and second sleeves 170, 175, respectively. In FIG.6A, the outer sleeve 170 is lined with a thin-wall insulative material200, such as PFA, or another material described below. Similarly, theinner sleeve 175 has an exterior insulative layer 202. These coatingmaterials can be lubricious as well as electrically insulative to reducefriction during reciprocation of the inner sleeve 175.

The insulative layers 200 and 202 described above can comprise alubricious, hydrophobic or hydrophilic polymeric material. For example,the material can comprise a bio-compatible material such as PFA,TEFLON®, polytetrafluroethylene (PTFE), FEP (Fluorinatedethylenepropylene), polyethylene, polyamide, ECTFE(Ethylenechlorotrifluoro-ethylene), ETFE, PVDF, polyvinyl chloride orsilicone.

Now turning to FIG. 6B, another variation of inner sleeve 175 isillustrated in a schematic view together with a tissue volume beingresected with the plasma electrode edge 180. In this embodiment, as inother embodiments in this disclosure, the RF source operates at selectedoperational parameters to create a plasma around the electrode edge 180of electrode sleeve 195 as is known in the art. Thus, the plasmagenerated at electrode edge 180 can resect and ablate a path P in thetissue 220, and is suited for resecting fibroid tissue and otherabnormal uterine tissue. In FIG. 6B, the distal portion of the resectingsleeve 175 includes a ceramic collar 222 which is adjacent the distaledge 180 of the electrode sleeve 195. The ceramic 222 collar functionsto confine plasma formation about the distal electrode edge 180 andfunctions further to prevent plasma from contacting and damaging thepolymer insulative layer 202 on the resecting sleeve 175 duringoperation. In one aspect of the invention, the path P resected in thetissue 220 with the plasma at electrode edge 180 provides a path Phaving an ablated width indicated at W, wherein such path width W issubstantially wide due to tissue vaporization. This removal andvaporization of tissue in path P is substantially different than theeffect of cutting similar tissue with a sharp blade edge, as in variousprior art devices. A sharp blade edge can divide tissue (withoutcauterization) but applies mechanical force to the tissue and mayprevent a large cross section slug of tissue from being cut. Incontrast, the plasma at the electrode edge 180 can vaporize a path P intissue without applying any substantial force on the tissue to thusresect larger cross sections of slugs or strips of tissue. Further, theplasma resecting effect reduces the cross section of tissue strip 225received in the reduced a cross-section region 190B of tissue-extractionlumen 160. FIG. 6B depicts a tissue strip 225 entering the reducedcross-section region 190B, wherein the tissue strip 225 has a smallercross-section than the lumen due to the vaporization of tissue. Further,the cross section of tissue 225 as it enters the larger cross-sectionlumen 190A results in even greater free space 196 around the tissuestrip 225. Thus, the resection of tissue with the plasma electrode edge180, together with the lumen transition from the smaller cross-section(190B) to the larger cross-section (190A) of the tissue-extraction lumen160 can significantly reduce or eliminate the potential for successiveresected tissue strips 225 to clog the lumen. Prior art resectiondevices with such small diameter tissue-extraction lumens typically haveproblems with tissue clogging.

In another aspect of the invention, the negative pressure source 225coupled to the proximal end of tissue-extraction lumen 160 (see FIGS. 1and 4) also assists in aspirating and moving tissue strips 225 in theproximal direction to a collection reservoir (not shown) outside thehandle 142 of the device.

FIGS. 7A-7B illustrate the change in lumen diameter of resecting sleeve175 of FIG. 6B. FIG. 8 illustrates the distal end of a variation ofresecting sleeve 175′ which is configured with an electrode resectingelement 195′ that is partially tubular in contrast to the previouslydescribed tubular electrode element 195 (FIGS. 5 and 6A). FIGS. 9A-9Bagain illustrate the change in cross-section of the tissue-extractionlumen between reduced cross-section region 190B′ and the increasedcross-section region 190A′ of the resecting sleeve 175′ of FIG. 8. Thus,the functionality remains the same whether the resecting electrodeelement 195′ is tubular or partly tubular. In FIG. 8A, the ceramiccollar 222′ is shown, in one variation, as extending only partiallyaround sleeve 175′ to cooperate with the radial angle of resectingelectrode element 195′. Further, the variation of FIG. 8 illustratesthat the ceramic collar 222′ has a larger outside diameter thaninsulative layer 202. Thus, friction may be reduced since the shortaxial length of the ceramic collar 222′ interfaces and slides againstthe interfacing insulative layer 200 about the inner surface of lumen172 of outer sleeve 170.

In general, one aspect of the invention comprises a tissue resecting andextracting device (FIGS. 10A-11C) that includes first and secondconcentric sleeves having an axis and wherein the second (inner) sleeve175 has an axially-extending tissue-extraction lumen therein, andwherein the second sleeve 175 is moveable between axially non-extendedand extended positions relative to a tissue-receiving window 176 infirst sleeve 170 to resect tissue, and wherein the tissue extractionlumen 160 has first and second cross-sections. The second sleeve 175 hasa distal end configured as a plasma electrode edge 180 to resect tissuedisposed in tissue-receiving window 176 of the first sleeve 170.Further, the distal end of the second sleeve, and more particularly, theelectrode edge 180 is configured for plasma ablation of a substantiallywide path in the tissue. In general, the tissue-extraction device isconfigured with a tissue extraction lumen 160 having a distal endportion with a reduced cross-section that is smaller than across-section of medial and proximal portions of the lumen 160.

In one aspect of the invention, referring to FIGS. 7A-7B and 9A-9B, thetissue-extraction lumen 160 has a reduced cross-sectional area in lumenregion 190B proximate the plasma resecting tip or electrode edge 180wherein said reduced cross section is less than 95%, 90%, 85% or 80% ofthe cross sectional area of medial and proximal portions 190A of thetissue-extraction lumen, and wherein the axial length of thetissue-extraction lumen is at least 10 cm, 20 cm, 30 cm or 40 cm. In oneembodiment of tissue resecting device 100 for hysteroscopic fibroidresection and extraction (FIG. 1), the shaft assembly 140 of the tissueresecting device is 35 cm inches.

FIGS. 10A-10C illustrate the working end 145 of the tissue resectingdevice 100 with the reciprocating resecting sleeve or inner sleeve 175in three different axial positions relative to the tissue receivingwindow 176 in outer sleeve 170. In FIG. 10 A, the resecting sleeve 175is shown in a retracted or non-extended position in which the sleeve 175is at it proximal limit of motion and is prepared to advance distally toan extended position to thereby electrosurgically resect tissuepositioned in and/or suctioned into window 176. FIG. 10B shows theresecting sleeve 175 moved and advanced distally to a partially advancedor medial position relative to tissue resecting window 176. FIG. 10Cillustrates the resecting sleeve 175 fully advanced and extended to thedistal limit of its motion wherein the plasma resecting electrode 180has extended past the distal end 226 of tissue-receiving window 176 atwhich moment the resected tissue strip 225 in excised from tissue volume220 and captured in reduced cross-sectional lumen region 190B.

Now referring to FIGS. 10A-10C, FIGS. 11A-11C and FIGS. 12A-12C, anotheraspect of the invention comprises “tissue displacement” mechanismsprovided by multiple elements and processes to “displace” and movetissue strips 225 (FIG. 12A) in the proximal direction in lumen 160 ofresecting sleeve 175 to thus ensure that tissue does not clog the lumenof the inner sleeve 175. As can be seen in FIG. 10A and the enlargedviews of FIGS. 11A-11C, one tissue displacement mechanism comprises aprojecting element 230 that extends proximally from distal tip 232 whichis fixedly attached to outer sleeve 170. The projecting element 230extends proximally along central axis 168 in a distal chamber 240defined by outer sleeve 170 and distal tip 232. In one embodimentdepicted in FIG. 11 A, the shaft-like projecting element 230, in a firstfunctional aspect, comprises a mechanical pusher that functions to pusha captured tissue strip 225 proximally from the small cross-sectionlumen 190B of resecting sleeve 175 (FIG. 12A) as the resecting sleeve175 moves to its fully advanced or extended position.

In a second functional aspect, the chamber 240 in the distal end ofsleeve 170 is configured to capture a volume of saline distending fluid244 (FIG. 12A) from the working space, and wherein the existing RFelectrodes of the working end 145 are further configured to explosivelyvaporize the captured fluid 244 to generate proximally-directed forceson tissue strips 225 resected and disposed in lumen 160 of the resectingsleeve 175 (FIGS. 12B and 12C). Both of these functional elements andprocesses (tissue displacement mechanisms) can apply a substantialmechanical force on the captured tissue strips 225 by means of theexplosive vaporization of liquid in chamber 240 and can function to movetissue strips 225 in the proximal direction in the tissue-extractionlumen 160. It has been found that using the combination of multiplefunctional elements and processes can virtually eliminate the potentialfor tissue clogging the tissue extraction lumen 160.

More particularly, FIGS. 12A-12C illustrate the functional aspects ofthe tissue displacement mechanisms and the subsequent explosivevaporization of fluid captured in chamber 240. In FIG. 12A, thereciprocating resecting sleeve 175 is shown in a medial positionadvancing distally wherein plasma at the resecting electrode edge 180 isresecting a tissue strip 225 that is disposed within lumen 160 of theresecting sleeve 175. In FIG. 12A-12C, it can be seen that the systemoperates in first and second electrosurgical modes corresponding to thereciprocation and axial range of motion of resecting sleeve 175 relativeto the tissue-receiving window 176. As used herein, the term“electrosurgical mode” refers to which electrode of the two opposingpolarity electrodes functions as an “active electrode” and whichelectrode functions as a “return electrode”. The terms “activeelectrode” and “return electrode” are used in accordance with conventionin the art—wherein an active electrode has a smaller surface area thanthe return electrode which thus focuses RF energy density about such anactive electrode. In the working end 145 of FIGS. 10A-11C, the resectingelectrode element 195 and its resecting electrode edge 180 must comprisethe active electrode to focus energy about the electrode to generate theplasma for tissue resection. Such a high-intensity, energetic plasma atthe electrode edge 180 is needed throughout stroke X indicated in FIG.12A-12B to resect tissue. The first mode occurs over an axial length oftravel of inner resecting sleeve 175 as it crosses the tissue-receivingwindow 176, at which time the entire exterior surface of outer sleeve170 comprises the return electrode indicated at 185. The electricalfields EF of the first RF mode are indicated generally in FIG. 12A.

FIG. 12 B illustrates the moment in time at which the distal advancementor extension of inner resecting sleeve 175 entirely crosses thetissue-receiving window 176 (FIG. 12A). At this time, the electrodesleeve 195 and its electrode edge 180 are confined within the mostlyinsulated-wall chamber 240 defined by the outer sleeve 170 and distaltip 232. At this moment, the system is configured to switch to thesecond RF mode in which the electric fields EF switch from thosedescribed previously in the first RF mode. As can be seen in FIG. 12B,in this second mode, the limited interior surface area 250 (FIG. 12C) ofdistal tip 232 that interfaces chamber 240 functions as an activeelectrode and the distal end portion of resecting sleeve 175 exposed tochamber 240 acts as a return electrode. In this mode, very high energydensities occur about surface 250 and such a contained electric field EFcan explosively and instantly vaporize the fluid 244 captured in chamber240. The expansion of water vapor can be dramatic and can thus applytremendous mechanical forces and fluid pressure on the tissue strip 225to move the tissue strip in the proximal direction in the tissueextraction lumen 160. FIG. 12C illustrates such explosive or expansivevaporization of the distention fluid 244 captured in chamber 240 andfurther shows the tissue strip 225 being expelled in the proximaldirection the lumen 160 of inner resecting sleeve 175.

FIG. 14 shows the relative surface areas of the active and returnelectrodes at the extended range of motion of the resecting sleeve 175,again illustrating that the surface area of the non-insulated distal endsurface 250 is small compared to surface 255 of electrode sleeve whichcomprises the return electrode.

Still referring to FIGS. 12A-12C, it has been found that a single powersetting on the RF source 150 and controller 155 can be configured both(i) to create plasma at the electrode resecting edge 180 of electrodesleeve 195 to resect tissue in the first mode, and (ii) to explosivelyvaporize the captured distention fluid 244 in the second mode. Further,it has been found that the system can function with RF mode-switchingautomatically at suitable reciprocation rates ranging from 0.5 cyclesper second to 8 or 10 cycles per second. In bench testing, it has beenfound that the tissue resecting device described above can resect andextract tissue at the rate of from 4 grams/min to 8 grams/min withoutany potential for tissue strips 225 clogging the tissue-extraction lumen160. In these embodiments, the negative pressure source 125 also iscoupled to the tissue-extraction lumen 160 to assist in applying forcesfor tissue extraction.

Of particular interest, the fluid-capture chamber 240 defined by sleeve170 and distal tip 232 can be designed to have a selected volume,exposed electrode surface area, length and geometry to optimize theapplication of expelling forces to resected tissue strips 225. In oneembodiment, the diameter of the chamber is 3.175 mm and the length is5.0 mm which taking into account the projecting element 230, provided acaptured fluid volume of approximately 0.040 mL. In other variations,the captured fluid volume can range from 0.004 mL to 0.080 mL.

In one example, a chamber 240 with a captured liquid volume of 0.040 mLtogether with 100% conversion efficiency in and instantaneousvaporization would require 103 Joules to heat the liquid from roomtemperature to water vapor. In operation, since a Joule is a W*s, andthe system reciprocate at 3 Hz, the power required would be on the orderof 311 W for full, instantaneous conversion to water vapor. Acorresponding theoretical expansion of 1700 x would occur in the phasetransition, which would results in up to 25,000 psi instantaneously(14.7 psi×1700), although due to losses in efficiency andnon-instantaneous expansion, the actual pressures would be much less. Inany event, the pressures are substantial and can apply significantexpelling forces to the captured tissue strips 225.

Referring to FIG. 12A, the interior chamber 240 can have an axial lengthfrom about 0.5 mm to 10 mm to capture a liquid volume ranging from about0.004 mL 0.01 mL. It can be understood in FIG. 12A, that the interiorwall of chamber 240 has an insulator layer 200 which thus limits theelectrode surface area 250 exposed to chamber 240. In one embodiment,the distal tip 232 is stainless steel and is welded to outer sleeve 170.The post element 248 is welded to tip 232 or machined as a featurethereof. The projecting element 230 in this embodiment is anon-conductive ceramic.

FIG. 13 shows the cross-section of the ceramic projecting element 230which may be fluted, and which in one embodiment has three fluteelements 260 and three corresponding axial grooves 262 in its surface.Any number of flutes, channels or the like is possible, for example fromtwo to about 20. The fluted design increases the availablecross-sectional area at the proximal end of the projecting element 230to push the tissue strip 225, while at the same time the three grooves262 permit the proximally-directed jetting of water vapor to impact thetissue exposed to the grooves 262. In one embodiment, the axial length D(FIG. 12A) of the projecting element 230 is configured to push tissueentirely out of the reduced cross-sectional region 190B of the electrodesleeve element 195. In another embodiment, the volume of the chamber 240is configured to capture liquid that when explosively vaporized providesa gas (water vapor) volume sufficient to expand into and occupy at leastthe volume defined by a 10% of the total length of extraction channel160 in the device, usually at least 20% of the extraction channel 160,often at least 40% of the extraction channel 160, sometimes at least 60%of the extraction channel 160, other times at least 80% of theextraction channel 160, and sometimes at least 100% of the extractionchannel 160.

As can be understood from FIGS. 12A to 12C, the distending fluid 244 inthe working space replenishes the captured fluid in chamber 240 as theresecting sleeve 175 moves in the proximal direction or towards itsnon-extended position. Thus, when the resecting sleeve 175 again movesin the distal direction to resect tissue, the interior chamber 240 isfilled with fluid 244 which is then again contained and is thenavailable for explosive vaporization as described above when theresecting sleeve 175 closes the tissue-receiving window 176. In anotherembodiment, a one-way valve can be provided in the distal tip 232 todraw fluid directly into interior chamber 240 without the need for fluidto migrate through window 176.

FIG. 15 illustrates another variation in which the active electrodesurface area 250′ in the second mode comprises a projecting element 230with conductive regions and non-conductive regions 260 which can havethe effect of distributing the focused RF energy delivery over aplurality of discrete regions each in contact with the captured fluid244. This configuration can more efficiently vaporize the captured fluidvolume in chamber 240. In one embodiment, the conductive regions 250′can comprise metal discs or washers on post 248. In other variation (notshown) the conductive regions 250′ can comprise holes, ports or pores ina ceramic material 260 fixed over an electrically conductive post 248.

In another embodiment, the RF source 150 and controller 155 can beprogrammed to modulate energy delivery parameters during stroke X andstroke Y in FIGS. 12A-12C to provide the optimal energy (i) for plasmaresection with electrode edge 180, and (ii) for explosively vaporizingthe captured fluid in chamber 240.

FIGS. 16A-16C illustrate another embodiment RF resecting probe 700 withworking end 702 comprising a tubular resection device adapted forelectrosurgical resection and extraction of targeted tissue from theinterior of a patient's body. However, in this embodiment, the innerresecting sleeve is configured to rotate instead of reciprocate as inthe previously-described embodiments.

Referring to FIG. 16A, the outer sleeve 705 comprises a metal tubularmember 708 that extends from a handle (not shown) to a working end 702that again carries a distal dielectric body 710 defining a window 712therein. The inner second sleeve or resecting sleeve 715 comprises ametal tubular member 718 that carries a distal dielectric body 720 witha windowed side 724 that is adapted to cooperate with window 712 in theouter sleeve 705.

FIGS. 16B-16C show the working end 702 of probe 700 with the rotatingresecting sleeve 715 and RF electrode edge 725 in two differentrotational positions with respect to outer sleeve 705 and window 712. InFIG. 16B, the inner sleeve 715 is rotated approximately 90° relative tothe outer sleeve 705. In FIG. 16C, the inner sleeve 715 is rotated 180°to a position relative to inner sleeve 715 to effectively close thewindow 712 defined by the outer sleeve 705. It can easily be understoodhow rotation of electrode edge 725 thus can resect tissue duringrotation and capture the tissue in the window-closed position within thetissue-receiving lumen 730 of the probe.

In this embodiment of FIGS. 16A-16C, the RF electrode edge 725 of theinner sleeve 715 comprises a first polarity electrode. The exteriorsurface 732 of the outer sleeve 705 comprises a second polarityelectrode as described in previous embodiments. As can be understoodfrom FIGS. 16A-16C, it is critical that the first and second polarityelectrode surfaces (725 and 732) are spaced apart by a predetermineddimension throughout the rotation of inner sleeve 715 relative to outersleeve 705. In one aspect the invention, the distal ends of the innerand outer sleeves comprise ceramic bodies 710 and 720 with an interface740 therebetween. In other words, the ceramic bodies 710 and 720 rotateabout interface 740 and the bodies provide exact electrode spacing ESbetween the first and second polarity electrodes 725 and 732.

Now referring to FIG. 17, it can be seen how the outer sleeve 705comprises as an assembly between the tubular metal sleeve 708 and thedielectric body 710, which in this variation can be a ceramic such aszirconium. In FIG. 17, it can be seen that the ceramic body 710 has athin wall 742 which can range in thickness from about 0.003″ and 0.010″wherein the ceramic extends 360° around window 712. Ceramic body 710 canthus be slidably inserted into and bonded to bore 728 in metal sleeve708.

Now turning to FIG. 18, the distal end of inner sleeve 715 is shownde-mated from the outer sleeve assembly 705 (see FIG. 16A). The tubularmetal sleeve 718 of FIG. 18 is fabricated to allow insertion of theceramic body 720 which supports the electrode edge 725 and provides arotational bearing surface about the interface 740 (see FIG. 16A). FIG.19 shows an exploded view of the inner sleeve assembly of FIG. 18. InFIG. 19, it can be seen that ceramic body 720 has a hemisphericalcross-sectional shape and includes an elongated slots 744 for receivingand supporting an electrode edge 725. FIG. 19 further shows metal sleeve718 without ceramic body 720 wherein the electrode edge 725 is cut froma rounded end sleeve 718. It can be understood that the slot 744 canreceive ceramic body 720 and thus the electrode edge 725 extends in aloop and under rotation will have a leading edge 745 and a trailing edge745′ depending on the direction of rotation. As used herein, the term‘leading edge’ refers to the electrode edge 725 extending around thedistal end of the sleeve 715 to its centerline on its rotational axis.

In one aspect of the invention, the tissue resecting probe 700 comprisesan outer sleeve 705 and an inner sleeve 715 that is rotatable to providewindow-open and window-closed positions and wherein the distal ends ofthe first and second sleeves 705, 715 include ceramic bodies 710, 720that provide surfaces on either side of a rotational interface 740.Further, the first and second sleeves provide ceramic bodies 710, 720that contact one another on either side of the rotational interface 740and thus provide a predetermined electrode spacing ES (FIG. 16A). In onevariation, the wall thickness of the ceramic body 710 is from 0.003″ to0.004″. Likewise, the wall thickness of ceramic body 720 can be from0.003″ to 0.004″. Thus, the radial dimension between the first andsecond polarity electrodes at a minimum in this variation is 0.006″. Inanother variation in which the inner sleeve 715 carries an outerpolymeric dielectric layer which can be 0.001″ in thickness to thusprovide an electrode spacing dimension ES of 0.004″. In other variationshaving a larger diameter, the dimension between the first and secondpolarity electrodes can range up to 0.030″. In general, the scope of theinvention includes providing a rotational tubular resection device withbi-polar electrodes spaced apart between 0.004″ inches and 0.030″ incheswherein the resecting sleeve 715 rotates about an interface 740 havingdielectric materials on either side thereof.

In the embodiment shown in FIGS. 16A-16C, the length of the window canrange from about 5 mm to 30 mm. The diameter of the probe working endcan range from about 3 mm to 6 mm or more. The rotational speed of theinner sleeve can range from 100 rpm to 5,000 rpm. In one embodiment, arotation ranging from about 200 rpm to 500 rpm resects tissueefficiently and allowed for effective tissue extraction as describedbelow.

In another aspect of the invention, referring to FIGS. 17, 20A and 20B,it can be seen that an opening 748 is provided in ceramic body 710 whichprovides exposure through the ceramic body 710 to metal sleeve 708 whichcomprises the first polarity electrode when assembled. Thus, the metalsleeve provides an interior electrode surface 750 that is exposed tointerior chamber 730. It can be understood that in this variation, theworking end 702 can function in two RF modes as described in theprevious reciprocating probe embodiments (see FIGS. 12A-12C). In thefirst RF mode, the exterior surface 732 of outer sleeve 705 functions asa first polarity electrode in the interval when the inner sleeve 715 andits second polarity electrode edge 725 rotates from the window-openposition of FIG. 16A toward the window-closed position of FIG. 16B. FIG.20A depicts this interval of rotation, wherein it can be seen that thefirst RF mode operates for approximately 180° of rotation of the innerresecting sleeve 715. In this position depicted in FIG. 20A, the leadingedge 745 and trailing edge 745′ of electrode edge 725 are exposed to theopen window 712 and electric fields EF extend to the first polarityelectrode surface 732 about the exterior of the probe and plasma isformed at leading edge 745 to resect tissue.

The second RF mode is shown in FIG. 20B, wherein the inner sleeve 715rotates to the window-closed position and the probe switches instantlyto such a second RF mode since the electrode edge 725 is exposed only tothe tissue-receiving lumen 730. It can be understood that the second RFmode operates only when the window 712 is closed as in FIGS. 16C and 20Bwhich causes the instant explosive vaporization of captured saline inthe lumen 730. In FIG. 20B, it can be seen that the electrode edge 725is exposed only to the interior of lumen 730 and electric fields EFextend between the leading and trailing electrode edges (745 and 745′)to the exposed electrode surface 750 to thus cause the explosivevaporization of captured saline. The vaporization occurs instantlywithin limited degrees of rotation of the inner sleeve, e.g., 5° to 20°of rotation, upon closing the window 712 to thereby expel the resectedtissue in the proximal direction as described previously. It has beenfound that saline captured in the interior channel 730 can be distal tothe resected tissue or adjacent to the resected tissue in the lumen andthe fluid expansion in the liquid-to-vapor transition will instantlyexpel the resected tissue outwardly or proximally in lumen 730.

FIG. 21 is a longitudinal sectional view of the working end 702corresponding to FIG. 20B wherein the electrical fields EF are confinedwithin the interior lumen 730 to thus cause the explosive vaporizationof captured saline. Thus, the second RF mode and the vaporization ofcaptured saline 754 as depicted in FIG. 20B will expel the resectedtissue 755 proximally within the tissue extraction channel 730 thatextends proximally through the probe to a collection reservoir asdescribed in previous embodiments. In general, a method of the inventionincludes capturing a tissue volume in a closed distal portion of aninterior passageway of an elongate probe and causing a phase transitionin a fluid proximate to the captured tissue volume to expand the fluidto apply a proximally directed expelling force to the tissue volume. Thetime interval for providing a closed window to capture the tissue andfor causing the explosive vaporization can range from about 0.01 secondto 2 seconds. A negative pressure source also can be coupled to theproximal end of the extraction lumen as described previously.

Now turning to FIG. 22, another variation of inner sleeve 715′ is shown.In this embodiment, the leading edge 745 and the trailing edge 745′ ofelectrode edge 725 are provided with different electricalcharacteristics. In one variation, the leading edge 745 is a highlyconductive material suited for plasma ignition as described previously.In this same variation shown in FIG. 22, the trailing edge 745′comprises a different material which is less suited for plasmaformation, or entirely not suited for plasma formation. In one example,the trailing edge 745′ comprises a resistive material (e.g., a resistivesurface coating) wherein RF current ignites plasma about the leadingedge 745 but only resistively heats the trailing 745′ edge to thusprovide enhanced coagulation functionality. Thus, the leading edge 745cuts and the trailing edge 745′ is adapted to coagulate the justresected tissue. In another variation, the trailing edge 745′ can beconfigured with a capacitive coating which again can be used forenhancing tissue coagulation. In yet another embodiment, the trailingedge 745′ can comprise a positive temperature coefficient of resistance(PTCR) material for coagulation functionality and further for preventingtissue sticking. In another variation, the trailing edge 745′ can have adielectric coating that prevents heating altogether so that the leadingedge 745 resects tissues and the trailing edge 745′ has noelectrosurgical functionality.

FIG. 23 illustrates another embodiment of inner sleeve component 718′ inwhich the electrode edge 725 has a leading edge 745 with edge featuresfor causing a variable plasma effect. In this embodiment, the projectingedges 760 of the leading edge 745 electrode will create higher energydensity plasma than the scalloped or recessed portions 762 which canresult in more efficient tissue resection. In another embodiment, theelectrode surface area of the leading edge 745 and trailing edge 745′can differ, again for optimizing the leading edge 745 for plasmaresection and the trailing edge 745′ for coagulation. In anotherembodiment, the trailing edge 745′ can be configured for volumetricremoval of tissue by plasma abrasion of the just resected surface sincethe trailing edge is wiped across the tissue surface. It has been foundthat a substantial amount of tissue (by weight) can be removed by thismethod wherein the tissue is disintegrated and vaporized. In general,the leading edge 745 and trailing edge 745′ can be dissimilar with eachedge optimized for a different effect on tissue.

FIG. 24 illustrates another aspect of the invention that can be adaptedfor selective resection or coagulation of targeted tissue. In thisvariation, a rotation control mechanism is provided to which can movethe inner sleeve 715 to provide the leading edge 745 in an exposedposition and further lock the leading edge 745 in such an exposedposition. In this locked (non-rotating) position, the physician canactivate the RF source and controller to ignite plasma along the exposedleading edge 745 and thereafter the physician can use the working end asa plasma knife to resect tissue. In another variation, the physician canactivate the RF source and controller to provide different RF parametersconfigured to coagulate tissue rather than to resect tissue. In oneembodiment, a hand switch or foot switch can upon actuation move andlock the inner sleeve in the position shown in FIG. 24 and thereafteractuate the RF source to deliver energy to tissue.

FIGS. 25A and 25B schematically illustrate another aspect of theinvention which relates to controller algorithms and sensor mechanismsfor moving the resecting sleeve or member at a selected speed andstopping movement of the resecting member at a predetermined stopposition relative to the window in the outer sleeve or member. Theselected stop position can consist of a partly window-open position, afully window-open position or a window-closed position. It should beappreciated that the system and method described below can be used indevices with a reciprocating resecting member, a rotating resectingmember or combination reciprocating-rotating resection member. Forconvenience, FIGS. 25A and 25B illustrate the principles of operatingthe controller and system with reference to a resection device having areciprocating resecting member. It should also be appreciated thatalgorithms and mechanisms can be used for any electrosurgical resectingdevice or a mechanical blade-type resecting device.

FIG. 25A depicts a tissue resecting device 800 that has a motor drivesystem 805 carried in handle portion 806 with the motor drive adapted toactuate the working end 810. As in previously described embodiments, thedevice 800 has an elongated shaft portion comprising first outer member815 fixed to handle 806 and moveable second member or resecting member820 that is configured to resect tissue in tissue-receiving window 822as the second member 820 reciprocates. The motor drive system 805comprises an electrical motor 824 (e.g., a brushless electric motor andgear reduction mechanism), electrical source 825 and motor shaft 826that drives a rotation-to-linear motion conversion mechanism 828. Auser-operated switch 830, such as a footswitch or handswitch is providedto start and stop actuation of the device. In one variation, a rotatabledrive collar 832 has an arcuate slot 835 that engages a pin 836 coupledto a keyed non-rotatable resecting member 820. As can be understood fromFIGS. 25A-25B, as the drive collar 832 and slot 835 rotate 360°, the pin836 and resecting member 820 are mechanically driven in the distaldirection and then in the proximal direction a selected dimension orstroke W (FIG. 25A) wherein the distal edge 840 of second member 820thus moves back and forth across window 822.

It has been found that particular reciprocation rates are optimal forcutting different tissues, and in one variation for resecting fibroidtissue, a reciprocation rate of 3 Hz to 5 Hz is optimal. It also hasbeen found that tight tolerances between the first and second members inthe shaft assembly as well as tissue density can affect the rate ofreciprocation for a given voltage provided to motor 824 from electricalsource 825. In one aspect of the invention, the system and controller850 are adapted to reciprocate the second member 820 at a selected rateno matter the system resistance or resistance to resection caused bytissue density. The controller 850 includes a microprocessor andalgorithm to achieve and maintain a reciprocation rate, which forexample can range from 1 Hz to 10 Hz, and may be of 3 Hz to 5 Hz forfibroid resection. In one variation shown in FIG. 25A, the drive system805 and controller 850 cooperate to function as a tachometer wherein amicroswitch 854 engages an engagement feature 856 in drive collar 832once each revolution of the collar. The engagement feature 856, such asan indent, actuates the microswitch 854 to send an electrical signal tocontroller 850 wherein a clock can determine and provide a signal ofrevolutions per minute (i.e., a tachometer signal) which in turncorresponds directly to reciprocation speed of the second member 820. InFIG. 25A, it can be seen that point X indicates the point in angularrotation of collar 832 and engagement feature 856 that the microswitch854 is actuated, which also corresponds to a particular position of thedistal edge 840 of second member 820 relative to window 822. Point X iscalled a reference point X for use in another controller algorithmdescribed below.

The controller 850 has an embedded algorithm that is responsive to thetachometer signal (i.e., measured rpm) to modulate voltage delivered tomotor 824 to achieve and maintain rotation of the drive collar 832 as aselected rpm. In the type of motor 824 used in the device 800, voltageis directly proportional to motor speed. At each revolution of drivecollar 832, the algorithm then reads rpm and can add voltage to increasespeed or subtract voltage to decrease speed, with the method depicted inFIG. 26. The algorithm can monitor or sample tachometer signals atintervals of less than 50 milliseconds, for example every 10 ms, 5 ms or1 ms. The controller algorithm is adapted to modulate motor voltage atintervals of less than 50 milliseconds, for example every 10 ms, 5 ms or1 ms. The controller algorithm can be adapted to modulate motor voltageup or down at a predetermined voltage increment or can modulate voltageup or down in at least first and second increments dependent the levelof variance between measured rpm and the targeted rpm. In anothervariation, the system and controller 850 can be configured for userselection of a plurality of selected speeds of driving the second memberrelative to the first member, and algorithms can be provided to achieveand maintain any selected speed. In another variation, the system andcontroller 850 can be configured for user selection of at least one ofrotating the second member, reciprocating the second member, androtating and reciprocating the second member, together with algorithmsas described above to achieve and maintain desired speeds. In othersimilar embodiments, the tachometer signal can be provided by an opticalsensor, a Hall effect sensor or any other suitable rpm sensor.

In another aspect of the invention, the controller 850 has anotherembedded algorithm that is used to stop reciprocation (or rotation) sothat the distal edge 840 of second member 820 is in a selected stopposition relative to window 822. The selected stop position can be afully window-open position, a window-closed position or an intermediatepartly-open position. In one electrosurgical embodiment adapted forcoagulation of tissue, the second member is stopped in a partly-openwindow position to provide optimal spacing between opposing polarityelectrodes and to permit outflows of distention fluid through the secondmember 820.

More in particular, referring to the method of FIG. 27, one variation ofresecting member stop algorithm reads the voltage level required toachieve and maintain the desired rpm of drive collar 832 (andcorresponding reciprocation rate) which results from use of thepreviously described algorithm. Thereafter, another algorithm calculatesthe resistance level that is overcome to drive the second member at theselected speed. The resistance level can be determined after a start-upcheck of the device, or can be averaged over the start-up check periodand for a period of time during surgery. The algorithm then comparesthis calculated resistance to a look-up table of known resistancescorrelated with a momentum parameter related to stopping movement of thesecond member 820 within the first member 815. Such resistance valuesare derived when the device 800 is operated before use in resectingtissue, so tissue density plays no role. Then, the algorithm is adaptedto de-energize the motor 824 at a predetermined point Y (see engagementfeature 856′ location in phantom view) to permit momentum to move thesecond member to a selected stop position Z (see engagement feature 856′location) as shown in FIG. 25B.

In operation, referring to FIGS. 25A-25B, assume the device 800 has beenoperated for multiple revolutions (prior to use in surgery) and thealgorithm has calculated the resistance value for the particular device,and thus has further calculated the rotational angle required totransition from an energized motor to a full stop of the second member,which is motion from point Y to point Z in FIG. 25B. Still further, thecontroller 850 has then calculated the rotational angle required tomaintain an energized motor from reference point X to point Y totransition from an energized motor to a full stop of the second member.Thereafter during use, the user will de-activate switch 830, which sendsa signal to controller 850. The de-activation signal can occur at anypoint in 360° rotation of drive collar 832. Following such ade-activation switch signal, the controller 850 maintains energydelivery to motor 824 until microswitch 854 is actuated at referencepoint X and further maintains energy delivery to motor 824 from point Xto point Y, and then de-energizes the motor 824 at point Y whichthereafter permits momentum to move the collar 832 from point Y to pointZ which is the selected stop position. The de-activation signal fromswitch 830 can occur with microswitch 854 within the engagement feature(indent) 856 and the controller 850 would still energize the motor 824from point X to point Y, and then de-energize the motor at point Y. Inone variation, the engagement feature would have a width that is lessthan the sampling rate of the controller 850, for example, an indent 856would require 5 ms of travel to activate and se-activate the microswitchand the controller 850 would sample or monitor for the signalde-activation signal every 1 ms.

It should be appreciated that the controller 850 and algorithm whencalculating the momentum parameter, one of several correspondingparameters could be used interchangeably, such as a time interval, anamount of rotational movement of drive collar 832 or an axial movementof the second member from a reference position to the selected stopposition.

In general, a tissue resecting device or system corresponding to theinvention comprises an assembly of tubular first and second members, anelectrical motor drive and controller configured for moving the secondmember to resect tissue in a window of the first member, a tachometeradapted to send motor drive rotational signals to the controller, and acontroller algorithm adapted to modulate motor voltage in response totachometer signals (i) to drive the second member at a predeterminedspeed and (ii) to calculate resistance to driving the second member atthe predetermined speed.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration and the above description of theinvention is not exhaustive. Specific features of the invention areshown in some drawings and not in others, and this is for convenienceonly and any feature may be combined with another in accordance with theinvention. A number of variations and alternatives will be apparent toone having ordinary skills in the art. Such alternatives and variationsare intended to be included within the scope of the claims. Particularfeatures that are presented in dependent claims can be combined and fallwithin the scope of the invention. The invention also encompassesembodiments as if dependent claims were alternatively written in amultiple dependent claim format with reference to other independentclaims.

What is claimed is:
 1. A tissue resecting device, comprising: anassembly of tubular first and second members; the second member having aresecting element at a distal end thereof; a handle; a motor drivesystem carried in the handle and a controller configured for moving thesecond member across a window of the first member; the motor drivesystem including a motor and a motor shaft driving a rotation-to-linearmotion conversion mechanism, wherein a distal edge of the second membermoves back and forth across the window of the first member from a windowopen position to a window closed position; wherein the controllerincludes an algorithm configured to stop reciprocation of the secondmember with the distal edge of the second member at a stop position inwhich the tissue-receiving window is partially open.
 2. The tissueresecting device of claim 1, wherein the rotation-to-linear motionconversion mechanism includes a rotatable drive collar.
 3. The tissueresecting device of claim 2, further comprising a microswitch, whereinthe microswitch engages an engagement feature of the drive collar onceeach revolution of the drive collar.
 4. The tissue resecting device ofclaim 3, wherein the engagement feature is an indent in the drivecollar.
 5. The tissue resecting device of claim 3, wherein themicroswitch sends an electrical signal to the controller for eachinstance the microswitch engages the engagement feature.
 6. The tissueresecting device of claim 5, wherein the controller is configured tode-energize the motor at a point Y between a reference point in whichthe microswitch engages the engagement feature and the stop position. 7.The tissue resecting device of claim 6, wherein the controller isconfigured to calculate point Y based on a calculated speed of rotationof the drive collar and calculated resistance of driving the secondmember.
 8. The tissue resecting device of claim 7, wherein thecontroller incudes an algorithm responsive to the calculated resistanceto de-energize the motor at point Y to permit momentum to move thesecond member to the stop position.
 9. The tissue resecting device ofclaim 8, wherein the algorithm is configured to compare the calculatedresistance to a look-up table of known resistances correlated with amomentum parameter related to stopping movement of the second member.10. The tissue resecting device of claim 2, wherein the drive collar isrotatable with the motor shaft.
 11. The tissue resecting device of claim10, wherein the drive collar includes an arcuate slot engaging a pinsecured to the second member.
 12. The tissue resecting device of claim11, wherein the pin and the second member reciprocate as the drivecollar rotates.
 13. The tissue resecting device of claim 1, wherein thecontroller is configured to stop the distal edge of the second member atthe stop position for coagulating tissue.
 14. The tissue resectingdevice of claim 13, wherein the first and second members includeopposing polarity electrodes for selectively resecting and coagulatingtissue.
 15. A tissue resecting device, comprising: an assembly includingan outer member having a tissue-receiving window and an inner membermovably positioned within the outer member, the inner member having aresecting element at a distal end thereof; a handle; a motor drivesystem carried in the handle and a controller configured for moving theresecting element of the inner member across the tissue-receiving windowof the outer member to resect tissue; the motor drive system including amotor and a motor shaft driving a rotation-to-linear motion conversionmechanism to reciprocate the inner member through at least one fulldistal and proximal reciprocation stroke via 360 degree rotation of therotation-to-linear motion conversion mechanism in a first rotationaldirection, wherein a distal edge of the resection element moves back andforth across the window of the outer member from a window open positionto a window closed position; wherein the controller includes analgorithm configured to stop reciprocation of the inner member with thedistal edge of the resecting element at a stop position in which thetissue-receiving window is partially open.
 16. The tissue resectingdevice of claim 15, wherein the rotation-to-linear motion conversionmechanism includes a rotatable drive collar.
 17. The tissue resectingdevice of claim 16, further comprising a microswitch, wherein themicroswitch engages an indent in the drive collar once each revolutionof the drive collar.
 18. The tissue resecting device of claim 17,wherein the microswitch sends an electrical signal to the controller foreach instance the microswitch engages the indent.
 19. The tissueresecting device of claim 18, wherein the controller is configured tode-energize the motor at a point Y between a reference point in whichthe microswitch engages the indent and the stop position.
 20. The tissueresecting device of claim 19, wherein the controller is configured tocalculate point Y based on a calculated speed of rotation of the drivecollar and calculated resistance of driving the inner member, andwherein the controller incudes an algorithm responsive to the calculatedresistance to de-energize the motor at point Y to permit momentum tomove the inner member to the stop position.